Inner vane for rotary devices

ABSTRACT

A sliding-vane rotary moving-fluid device. Radially slidable in each rotor slot are an outer vane and a thinner contiguous inner vane. Selected outward pressures on the inner vane and on leading and trailing portions of the outer vane provide proper net pressure distributions for tracking of the outer vane on a cam ring while traversing sealing spaces and port spaces alternately during rotation.

United States Patent 1151 3,640,651

Johnson Feb. 8, 1972 [54] INNER VANE FOR ROTARY DEVICES 3,481,27612/1969 Adams et al. ..4l8/269 X [72] Inventor: Harry T. Johnson,Westerville, Ohio FOREIGN PATENTS 0 APPLICATIONS 1 Assignee: The BatwlleDevelopment Corporation. 36,520 2/1912 Sweden ..418/268 Columbus, OhioPrimary Examiner-Carlton R. Croyle [22] Ffled' Aug. 1970 AssistantExaminer-Richard E. Gluck [21] Appl. No.: 68,398 Attorney-Gray, Mase andDunson 57 ABSTRACT [52] US. Cl ..418/269 l 51 1 1111. C1. ..F04c 1 00,F04C 17/00 A sliding-vane rotary moving-fluid device- Radially Slidablein 58 Field of Search ..4l8/268,269, 82, 26, 180 each rotor Slot are anOuter vane and a thinner contiguous inner vane. Selected outwardpressures on the inner vane and 56] Reerems Cited on leading andtrailing portions of the outer vane provide proper net pressuredistributions for tracking of the outer vane UNITED STATES PATENTS on acam ring while traversing sealing spaces and port spaces alternatelyduring rotation. 710,577 10/1902 Hawkins ..4l8/269 X 3,362,340 l/l968Adams ..4l8/269 11 Claims, 2 Drawing Figures INNER VANE FOR ROTARYDEVICES BACKGROUND OF THE INVENTION This invention relates tosliding-vane rotary moving-fluid devices. It has to do particularly withimprovements in the distribution of pressure on the vanes to provideoptimum tracking of the vanes on the cam ring while minimizing wear onthe relatively moving surfaces. The problems of imperfect tracking andexcessive wear in sliding-vane rotary movingfluid devices, such as pumpsand motors, have been serious and persistent ones. The present inventionprovides substantial improvements in dealing with both problems.

The present invention provides undervane hydrostatic pressuredistributions that cause the vane assembly to track the cam ring contourwithout liffing off the cam surface, while avoiding any excessiveloading between the vane tip and the cam surface. This requiresvariation in the undervane pressure distributions during rotation,because the hydrostatic pressure forces on the vane tip bearing surfacevary according to whether inlet pressure or outlet pressure is presentahead of the vane assembly and according to which pressure is presentbehind the vane assembly during its rotation. The variations that takeplace in the radially inward forces on the vane tip bearing surfacedepend also on the contour of the tip surface and on whether the tip isdesigned for boundary lubrication or to promote hydrodynamiclubrication.

The undervane pressure distributions for the various positions of thevane assembly need not provide exact hydrostatic balance. In fact acontrolled radial unbalance is generally preferable to assure propertracking of the vane tip on the cam ring. In proper tracking, thebearing surface of the vane tip is provided with sufficient outwardloading to maintain substantial contact with the cam ring. The tipsupports the net radial acceleration loading of the vane assembly andthe selected hydrostatic radial unbalance applied to the vane. Duringinward stroking the tip also supports the resulting radial drag forces.

SUMMARY OF THE INVENTION A typical sliding-vane rotary moving-fluiddevice according to the present invention comprises a cylindrical rotorhaving outer vanes slidable in substantially radial outer vane slotstherein and inner vanes slidable in substantially radial inner vaneslots extending inwardly from the outer vane slots, the tip of eachouter vane maintaining substantial contact with the inner cylindricalsurface of a cam surrounding the rotor as it traverses sealing spacesand port spaces alternately during rotation; pressure means formaintaining the outer edge of each inner vane in contact with a portionof the inner edge of the adjacent outer vane, to form a leading chamberin the outer vane slot inside the inner edge of the outer vane and aheadof the leading surface of an outer portion of the inner vane and to forma trailing chamber in the outer vane slot inside the inner edge of theouter vane and behind the trailing surface of an outer portion of theinner vane; and means for applying a predetermined sequence of forcesduring rotation to each leading chamber and to each trailing chamber.The outer edge of the inner vane in each slot typically is thinner thanthe inner edge of the outer vane therein and contacts it in a regionbetween the leading surface and the trailing surface of the outer vane.

The pressure means typically comprises means for continuously applyingfluid pressure against the inner edge of the inner vane, as bycommunicating a region contiguous to the inner edge of the inner vanewith a region in the device having a fluid pressure therein that isgreater than the lowest pressure encountered by the outer vanes.

The force applying means typically comprises means for communicatingeach leading chamber with the region between the rotor and the camimmediately ahead of the outer vane during rotation, and means forcommunicating each trailing chamber with the region between the rotorand the cam immediately behind the outer vane during rotation. Typicalcommunicating means may comprise an opening in the rotor extendingbetween the leading chamber in each outer vane slot, the trailingchamber in the next outer vane slot ahead, and a region of the outersurface of the rotor between the slots, or separate passages may beprovided in the rotor from the leading and trailing chambers torespective regions of the outer surface of the rotor immediately aheadof and behind the outer vane slot.

The areas of the inner edge of the outer vane in the leading andtrailing chambers and the area of the inner edge of the inner vane areselected such that the pressures thereon provide a predetermineddistribution of net forces on the tip of the outer vane for maintainingproper tracking of the tip with the cam during rotation. The tip of eachouter vane typically either is shaped to maintain substantial contactwith the inner surface of the cam essentially along a line substantiallyparallel to the leading and trailing edges of the outer vane, or elsecomprises a pivotable member having a substantial surface in substantialcontact with the inner surface of the cam.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a transverse cross-sectionalview of a typical sliding-vane rotary moving-fluid device according tothe present invention.

FIG. 2 is a similar view of a portion of a device similar to that ofFIG. 1 but with differences in some details.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, a sliding-vanerotary moving-fluid device 10 is shown similar to the device in FIG. 3of United States Pat. application, Ser, No. 15,377 of David L. Thomasfor Vane Tracking in Rotary Devices, and including a preferredembodiment of the present invention. For convenience, the device of FIG.1 is described herein as a singlelobe pump. From the disclosure of suchan embodiment, it will be apparent how the invention can be modified inroutine ways for incorporation in other rotary moving-fluid devices suchas fluid motors and other pumps, which may have more than one lobe, suchas the pumps and other devices disclosed in the patent applicationmentioned above and in US. Pat. Nos. 3,407,742 and 3,514,232.

A cylindrical rotor 11 has outer vanes 12 slidable in substantiallyradial outer vane slots 13 therein, and inner vanes 14 slidable insubstantially radial inner vane slots 15 extending inwardly from theouter vane slots 13. The tip 16 of each outer vane 12 maintainssubstantial contact, as indicated at 17, with the inner cylindricalsurface 18 of a cam 19 surrounding the rotor 11 as the vane 12 traversessealing spaces 20, 22 and port spaces 21, 23 alternately duringrotation. A very thin film of lubricant normally is present in theregion of substantial contact at 17 between the tip 16 of the outer vane12 and the inner cylindrical surface 18 of the cam 19.

The rotor 11 is rigidly mounted on a shaft 24 having an axis 25, theposition of which may either be fixed or variable with respect to theaxis 26 of the inner cylindrical surface 18 of the cam 19. The shaft 24and the rotor 11 thereon rotate in a clockwise direction as is indicatedby the arrow 27. The space between the rotor 11 and the cam 19 isenclosed by an end plate 28 fixedly mounted at each end of the cam 19 inclose slidable substantial contact with the rotor 11, a thin film oflubricant normally being present between the rotor 11 and each end plate28. The periphery of the end plate 28 in FIG. 1 is indicated at 29.

The end plate 28 contains an annular chamber 30 between the shaft 24 andthe surface 31 for communicating a region 32 contiguous to the inneredge 33 of each inner vane 14 with a region in the device 10 having afluid pressure therein that is greater than the lowest pressureencountered by the outer vanes 12. In the pump of FIG. 1 this region canconveniently be the port 21, where outlet pressure is present, or anyother conveniently located region having a suitable pressure greaterthan the inlet pressure at the port 23. In a fluid motor the chamber 30would communicate with an inlet port or other region having suitablepressure greater than the outlet pressure of the motor.

The communicating chamber 30 thus provides pressure means formaintaining the outer edge 34 of each inner vane 14 in contact with aportion of the inner edge 35 of the adjacent outer vane 12, to form aleading chamber 36 in the outer vane slot 13 inside the inner edge 35 ofthe outer vane 12 and ahead of the leading surface 37 of an outerportion of the inner vane 14, and to form a trailing chamber 38 in theouter vane slot 13 inside the inner edge 35 of the outer vane 12 andbehind the trailing surface 39 of an outer portion of the inner vane 14.Since the annular chamber 30 communicates the regions 32 with the regionof relatively high pressure at all positions of the rotor 11, therelatively high fluid pressure is continuously applied against the inneredge 33 of each inner vane 14.

The outer edge 34 s the inner vane 14 in each slot 13, is thinner thanthe inner edge 35 of the outer vane 12 therein and contacts it in aregion between the leading surface 40 and the trailing surface 41 of theouter vane 12.

An annular portion of the rotor 11 approximately midway between its endsis cut out from the outer surface 44 to an inner surface 45, thusforming an opening 50, 51, 52, 53, 54, 55 in the rotor 11 extendingbetween the leading chamber 36 in each outer vane slot 13, the trailingchamber 38 in the next outer vane slot 13 ahead, and a region of theouter surface 44 of the rotor 11 between the successive slots 13. Theopenings 5055 communicate each leading chamber 36 with the regionbetween the rotor 11 and the cam 19 immediately ahead of the outer vane12 during rotafion while at the same time communicating each trailingchamber 38 with the region between the rotor 11 and the cam 19immediately behind the outer vane 12 during rotation. Thus the openings50-55 apply a predetermined sequence of forces, by virtue of thepressures in the regions ahead and behind, to each leading chamber 36and to each trailing chamber 38 during rotation of the rotor I 1.

In FIG. 2, showing a modified form of the device of FIG. 1, the outervane 12' is so designated because it differs from the outer vanes 12 inFIG. 1, being a single member without a separate tip 16, and differingin shape from the outer vanes 12 in FIG. 1. The rotor 11 in FIG. 2 is sodesignated because it differs from the rotor 11 of FIG. 1, havingseparate passages 58, 59 rather than the continuous openings 50-55. Thepassage 58 in the rotor 11 communicates from the leading chamber 36 ofthe outer vane slot 13 to the region of the outer surface 44 of therotor 11 immediately ahead of the outer vane slot 13. Similarly thepassage 59 communicates from the trailing chamber 38 to the region ofthe outer surface 44 immediately behind the outer vane slot 13. Thus aleading passage 58 communicates each leading chamber 36 with the regionbetween the rotor 11' and the cam 19 immediately ahead of the outer vane12' during rotation, and a trailing passage 59 communicates eachtrailing chamber 38 with the region between the rotor 11 and the cam 19immediately behind the outer vane 12' during rotation, to apply apredetermined sequence of forces during rotation to each leading chamber36 and to each trailing chamber 38.

In both forms of the device, the areas of the inner edge 35 of the outervane 12 or 12' in the leading chamber 36 and the trailing chamber 38 andthe area of the inner edge 34 of the inner vane 14 are selected suchthat the pressures on the areas provide a predetermined distribution ofnet forces on the tip of the outer vane 12 or 12' for maintaining propertracking of the tip with the cam 19 during rotation.

Suitable distributions of force in the device of FIG. 1 are representedby the lengths of the arrows and the shapes of the curves at 6065. Whenthe tip 16 of an outer vane 12 is in substantial contact, as indicatedat 17, with the pumping lap space of the cam 19, the distribution offorces on the tip 16 is approximately as indicated at 60, varying from arelatively low force on the trailing end of the tip 16 to asubstantially higher force at the leading end. The forces on outer vanetips 16 in the outlet port space 21 of the cam 19 are approximately asshown at 61 and 62, being the same relatively high pressure over theentire outer surface of each outer vane tip 16. The force distributionon the outer surface of an outer vane tip 16 in substantial contact withthe sealing lap space 22 of the cam 19 is approximately as shown at 63,being relatively high at the trailing edge of the tip 16 and relativelylow at the leading edge. The forces on outer vane tips 16 in the inletport space 23 of the cam 19 are approximately as shown at 64 and 65,being the same relatively low pressures over the entire outer surface ofeach outer vane tip 16.

The location and the width of the inner vane [4 determine the magnitudeof the controlled radial hydrostatic unbalance on both the pumping lapspace 20 and the sealing lap space 22. The unbalance on the inlet port23 is a function of the width of the inner surface 33 of the inner vane14 and the magnitude of the pressure differential between the inlet port23 and the outlet port 21. The radial hydrostatic pressure on the outletport 21 is balanced, since the entire vane assembly is exposed to theoutlet pressure. The ability of the vane assembly to track on the outletport 21 thus depends on the accelerations that are produced, asdetermined by the contour of the inner surface 18 of the cam ring 19throughout the outlet port space 21.

The use of the inner vane 14 as disclosed herein enables a net radiallyoutward force to be applied to the vane assembly to assure tracking thatis independent of the rotational speed of the device, except on theoutlet port 21. The selection of the undervane pressure distribution toprovide the proper net force is determined by the pressure distributionon the bearing surface 17 of the tip 16 in FIG. 1.

In FIG. 2 an additional degree of freedom is provided in controlling thedistribution of forces. In FIG. 2 the tip of the outer vane 12' isshaped to maintain substantial contact with the inner surface 18 of thecam 19 essentially along a line between the leading and trailing edgesof the outer vane 12. Considering a plane 72 through the line ofsubstantial contact and parallel to the leading edge 70 and the trailingedge 71 of the inner vane slot 15, the distribution of forces is afunction of the position of the plane 72 between the edges 70 and 71.

A larger unbalance could be provided by communicating the full outletpressure to the entire inner edge 35 of the outer vane 12, 12, but thiswould overload the bearing surface of the vane tip on the inlet port 23,and the unbalance would be greater than is necessary for properoperation in the lap spaces 20 and 22. The use of the separate innervane 14 enables the designer to provide the optimum magnitude ofunbalance in each lap space 20, 22, while minimizing the loading of thetip of the outer vane l2, 12' on the inlet port 23.

The contact between the outer edge 34 of the inner vane 14 and the inneredge 35 of the adjacent outer vane 12 provides a positive seal betweenthe leading chamber 36 and the trailing chamber 38 in the outer vaneslot 13 when the vane assembly is subjected to a differential pressure.The radially outward differential pressure provided in the region 32 tothe inner vane 14 assures proper outward stroking of the outer vane l2,12 on the inlet port 23.

While the forms of the invention herein disclosed constitute presentlypreferred embodiments, many others are possible. it is not intended tomention all of the possible equivalent forms or ramifications of theinvention. It is to be understood that the terms used herein are merelydescriptive rather than limiting, and that various changes may be madewithout departing from the spirit or scope of the invention.

Iclaim:

1. A sliding-vane rotary moving-fluid device, comprising:

a cylindrical rotor having outer vanes slidable in substantially radialouter vane slots therein and inner vanes slidable in substantiallyradial inner vane slots extending inwardly from the outer vane slots,the tip of each outer vane maintaining substantial contact with theinner cylindrical surface of a cam surrounding the rotor as it traversessealing spaces and port spaces alternately during rotation;

pressure means for maintaining the outer edge of each inner vane incontact with a portion of the inner edge of the adjacent outer vane, toform a leading chamber in the outer vane slot inside the inner edge ofthe outer vane and ahead of the leading surface of an outer portion ofthe inner vane and to form a trailing chamber in the outer vane slotinside the inner edge of the outer vane and behind the trailing surfaceof an outer portion of the inner vane; and

means for applying a predetermined sequence of forces during rotation toeach leading chamber and to each trailing chamber.

2. A device as in claim 1, wherein the outer edge of the inner vane ineach slot is thinner than the inner edge of the outer vane therein andcontacts it in a region between the leading surface and the trailingsurface of the outer vane.

3. A device as in claim 1, wherein the pressure means comprises meansfor continuously applying fluid pressure against the inner edge of theinner vane.

4. A device as in claim 3, wherein the pressure applying means comprisesmeans for communicating a region contiguous to the inner edge of theinner vane with a region in the device having a fluid pressure thereinthat is greater than the lowest pressure encountered by the outer vanes.

5. A device as in claim 4, wherein the force applying means comprisesmeans for communicating each leading chamber with the region between therotor and the cam immediately ahead of the outer vane during rotation.

6. A device as in claim 5, wherein the force applying means comprisesalso means for communicating each trailing chamber with the regionbetween the rotor and the cam immediately behind the outer vane duringrotation.

7. A device as in claim 6, wherein the communicating means comprise anopening in the rotor extending between the leading chamber in each outervane slot. the trailing chamber in the next outer vane slot ahead, and aregion of the outer surface of the rotor between the slots.

8. A device as in claim 6, wherein the communicating means comprisepassages in the rotor from the leading and trailing chambers torespective regions of the outer surface of the rotor immediately aheadof and behind the outer vane slot.

9. A device as in claim 6, wherein the areas of the inner edge of theouter vane in the leading and trailing chambers and the area of theinner edge of the inner vane are selected such that the pressuresthereon provide a predetermined distribution of net forces on the tip ofthe outer vane for maintaining proper tracking of the tip with the camduring rotation.

10. A device as in claim 1, wherein the tip of each outer vane is shapedto maintain substantial contact with the inner surface of the camessentially along a line substantially parallel to the leading andtrailing edges of the outer vane.

11. A device as in claim 1, wherein the tip of each outer vane comprisesa pivotable member having a substantial surface in substantial contactwith the inner surface of the cam.

1. A sliding-vane rotary moving-fluid device, comprising: a cylindricalrotor having outer vanes slidable in substantially radial outer vaneslots therein and inner vanes slidable in substantially radial innervane slots extending inwardly from the outer vane slots, the tip of eachouter vane maintaining substantial contact with the inner cylindricalsurface of a cam surrounding the rotor as it traverses sealing spacesand port spaces alternately during rotation; pressure means formaintaining the outer edge of each inner vane in contact with a portionof the inner edge of the adjacent outer vane, to form a leading chamberin the outer vane slot inside the inner edge of the outer vane and aheadof the leading surface of an outer portion of the inner vane and to forma trailing chamber in the outer vane slot inside the inner edge of theouter vane and behind the trailing surface of an outer portion of theinner vane; and means for applying a predetermined sequence of forcesduring rotation to each leading chamber and to each trailing chamber. 2.A device as in claim 1, wherein the outer edge of the inner vane in eachslot is thinner than the inner edge of the outer vane therein andcontacts it in a region between the leading surface and the trailingsurface of the outer vane.
 3. A device as in claim 1, wherein thepressure means comprises means for continuously applying fluid pressureagainst the inner edge of the inner vane.
 4. A device as in claim 3,wherein the pressure applying means comprises means for communicating aregion contiguous to the inner edge of the inner vane with a region inthe device having a fluid pressure therein that is greater than thelowest pressure encountered by the outer vanes.
 5. A device as in claim4, wherein the force applying means comprises means for communicatingeach leading chamber with the region between the rotor and the camimmediately ahead of the outer vane during rotation.
 6. A device as inclaim 5, wherein the force applying means comprises also means forcommunicating each trailing chamber with the region between the rotorand the cam immediately behind the outer vane during rotation.
 7. Adevice as in claim 6, wherein the communicating means comprise anopening in the rotor extending between the leading chamber in each outervane slot, the trailing chamber in the next outer vane slot ahead, and aregion of the outer surface of the rotor between the slots.
 8. A deviceas in claim 6, wherein the communicating means comprise passages in therotor from the leading and trailing chambers to respective regions ofthe outer surface of the rotor immediately ahead of and behind the outervane slot.
 9. A device as in claim 6, wherein the areas of the inneredge of the outer vane in The leading and trailing chambers and the areaof the inner edge of the inner vane are selected such that the pressuresthereon provide a predetermined distribution of net forces on the tip ofthe outer vane for maintaining proper tracking of the tip with the camduring rotation.
 10. A device as in claim 1, wherein the tip of eachouter vane is shaped to maintain substantial contact with the innersurface of the cam essentially along a line substantially parallel tothe leading and trailing edges of the outer vane.
 11. A device as inclaim 1, wherein the tip of each outer vane comprises a pivotable memberhaving a substantial surface in substantial contact with the innersurface of the cam.